Showing papers on "Deformation (meteorology) published in 1978"
TL;DR: In this article, the median and lateral cracks around Vickers and small-diameter spherical indentations in soda-lime glass have been studied and sectioned to alloy a study of the subsurface deformation by making the indentations on and near the tip of a pre-existing crack, which is important to the application of indentation technique in determining fracture mechanics parameters as well as to the abrasion, erosion and wear processes in brittle materials.
Abstract: The median and lateral cracks around Vickers and small-diameter spherical indentations in soda-lime glass have been studied. The indentations were sectioned to alloy a study of the subsurface deformation by making the indentations on and near the tip of a pre-existing crack. These observations are important to the application of indentation technique in determining fracture mechanics parameters as well as to the abrasion, erosion and wear processes in brittle materials.
186 citations
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184 citations
Patent•
11 Dec 1978TL;DR: A sensor for measuring stress, temperature, pressure, sound, etc. as mentioned in this paper is composed of a light source which injects light into one end of a waveguide, a deformer contacting and deforming the waveguide to cause light to couple from originally excited modes to other modes, and an optical detector to detect the change in light coupling caused by deformation.
Abstract: A sensor for measuring stress, temperature, pressure, sound, etc. comprising an optical waveguide, preferably an optical fiber waveguide, a light source which injects light into one end of the waveguide, a deformer contacting and deforming the waveguide to cause light to couple from originally excited modes to other modes, and an optical detector to detect the change in light coupling caused by deformation of the waveguide.
180 citations
Journal Article•
TL;DR: In this article, the tensile deformation and fracture of pearlite were studied using high-resolution 200-kV semi-volumetric sensors and a high-frequency 200-KV semiuser.
Abstract: Dynamic studies of the tensile deformation and fracture of pearlite using high-resolution 200-KV sem
178 citations
TL;DR: In this article, a theory for the initial planar deformation of dilatant granular materials based on a kinematic proposal of R. Butterfield and R.M. Harkness is presented.
Abstract: A theory for the initial planar deformation of dilatant granular materials based on a kinematic proposal of R. Butterfield and R.M. Harkness (1972) is presented. The theory introduces an additional parameter called the angle of dilatancy into the traditional structure of plasticity theories for granular materials and soils. When the angle of dilatancy is zero, the present theory reduces to the theory introduced by A.J.M. Spencer in 1964. When the angle of dilatancy is equal to the angle of internal friction, the present theory reduces to the planar form of the theory introduced by D. C. Drucker and W. Prager in 1952. The properties of the theory presented here include coincidence of the stress and velocity characteristics, realistic energy dissipation predictions, and, in general, non-coincidence of the principal axes of stress and strain-rate. However, the angle of dilatancy is assumed to be a constant in this analysis and it does not decrease to zero with increased monotonic shearing deformation as experiment requires that it should, the theory therefore being limited to the initial deformation of dilatant granular materials.
166 citations
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159 citations
TL;DR: In this paper, the Taylor-Bishop-Hill analysis was used to simulate the deformation process of c-axis fabrics in a mylonite hand specimen and found that the microstructures reflect a combination of dynamic recovery and dynamic recrystallization processes, rather than from the effects of modifying preexisting or co-developing deformation fabrics.
137 citations
TL;DR: The cross sections for the fusion of the spherical and deformed isotopes of Sm measured at bombarding energies spanning the fusion barrier indicate the importance of nuclear deformation for the nuclear fusion process as discussed by the authors.
Abstract: The cross sections for the fusion of $^{16}\mathrm{O}$ with the spherical and deformed isotopes of Sm measured at bombarding energies spanning the fusion barrier indicate the importance of nuclear deformation for the fusion process. Calculations based on the usual static treatment of deformation effects, however, show significant discrepancies with the experimental data.
126 citations
TL;DR: In this article, Hartree-Fock-Bogolyubov calculations are carried out for even Mo isotopes, to assess quantitatively the role of the isoscalar neutron-proton interaction in producing deformation in nuclei with large neutron excesses.
TL;DR: In this article, it was shown that the deformation of linear polyethylene is associated with the development of recoverable strain, and a technique was developed to determine the magnitude of the recovery forces.
Abstract: In the light of the finding that the deformation of linear polyethylene is associated with the development of recoverable strain, a technique has been developed to determine the magnitude of the recovery forces. The difference between the applied force and the recovery force represents the effective force which acts on the anelastic processes and a consideration of the kinetics of deformation suggests that the anelastic process consists of the co-operative movement of a number of molecular segments. The extrapolated yield point appears to be associated with the effective force and has no particular structural significance, in that it corresponds merely to the point of maximum curvature in the relationship between effective stress and rate of deformation.
Journal Article•
TL;DR: In this article, the relative roles of limit equilibrium and deformation analyses are discussed, the principles of limit equilibria analysis are outlined, and details of the techniques commonly used in practice.
Abstract: The relative roles of limit equilibrium and deformation analyses are discussed, the principles of limit equilibrium analysis are outlined, and details (with examples) are given of the techniques commonly used in practice. Total effective stress analysis, total stress analysis of soil slopes, effective stress analysis of soil slopes, pore-pressure distribution and the analysis of rock slopes are detailed. The use of deformation analysis in the design of slopes is considered and its limitations are pointed out. It is noted that a deformation analysis, particularly an analysis utilizing the finite element method must include the following: the stress field must satisfy equilibrium at every point; boundary conditions of stress and deformation must be satisfied.
TL;DR: In this article, the system of thermodynamic fundamental equations for bulk phases and interfaces has been studied within the frames of the completely elastic solid model, and the dependence of surface properties on strains has been considered.
TL;DR: The deformation plot is shown to be ideal for display of ellipsoid shape, as is its logarithmic transformation for the display of deformation paths of coaxial deformations as mentioned in this paper.
Abstract: The deformation plot is shown to be ideal for the display of ellipsoid shape, as is its logarithmic transformation for the display of deformation paths of coaxial deformations. Other plots which have been proposed can be derived from the deformation plot by various geometric transformations and by the superposition of other coordinate axes. These variants of the deformation plot are less convenient to use. The deformation plot may also be used for the construction of deformation paths. This use depends on the definition of a number of different types of deformation ellipsoid. In particular, in deformations involving volume change, the shape change arising from the volume change needs to be represented by an ellipsoid. Under these conditions coaxial deformation paths of any imaginable complexity can be easily constructed on the deformation plot. For non-coaxial deformation, matrix representation of the deformation ellipsoids allows deformation paths to be computed, but graphic representation of these results requires both the deformation plot and a stereonet.
01 Jan 1978
TL;DR: In this paper, the authors describe the development of a finite-element model for analyzing the sheet-metal forming processes, where materials are assumed to be rigid-plastic with the view that the usefulness of an analysis method depends largely on solution accuracy and computation efficiency.
Abstract: The paper describes the development of a finite-element model for analyzing the sheet-metal forming processes. Materials are assumed to be rigid-plastic with the view that the usefulness of an analysis method depends largely on solution accuracy and computation efficiency.
TL;DR: Pitting corrosion of a cold-worked 18Cr 10Ni 2Mo stainless steel in an 0.1M NaC1 solution was studied using a potentiostatic technique, and statistical measurements of the pit dimensions and distribution were made using a metallographic image analyzer as discussed by the authors.
TL;DR: In this paper, the occurrence of deformation twins and the residual volume fraction were observed to depend upon peak pressure, P, pulse duration, Δt, and the average grain size of the initial sheet material, D.
TL;DR: The mechanical effect of myocardial fiber orientation and the ability of muscle layers to deform differentially are illustrated and the implications of the deformation components are discussed first separately and then in a coordinated fashion.
Abstract: A biplane cineradiographic technique was used to measure deformation of the myocardium as indicated by small lead spheres implanted into the anterior left ventricular wall of anesthetized dogs. Deformation was resolved into nine separate components for each of the epicardial, middle, and endocardial layers. The data illustrate the mechanical effect of myocardial fiber orientation and the ability of muscle layers to deform differentially. In order to present an overview of all the results, the implications of the deformation components are discussed first separately and then in a coordinated fashion.
TL;DR: In this paper, the Luders deformation in polycrystalline iron has been examined using specially shaped specimens under various conditions, and the results obtained are summarized as follows: 1. The macroscopic deformation starts in a narrow region at the upper yield stress and rapidly propagates across the cross-section of specimen.
TL;DR: In this article, a new formulation of the equations of membrane theory in nonlinear elasticity is described, based on the consistent use of certain conjugate variables averaged through the (undeformed) thickness of the thin shell which the membrane approximates.
Abstract: A new formulation of the equations of membrane theory in non-linear elasticity is described. It is based on the consistent use of certain conjugate variables averaged through the (undeformed) thickness of the thin shell which the membrane approximates. The deformation gradient is taken as the basic measure of deformation, and its average value as the membrane measure of deformation. It is shown that the average elastic strain energy can be regarded as a function of the average deformation gradient to within an error which is of the second order in a certain small parameter. Moreover, to the same order, the average strain energy is a potential function for the average nominal stress. This means that the averages of the conjugate variables (nominal stress and deformation gradient) are also conjugate. In terms of the average conjugate variables, the membrane equilibrium equations are obtained by averaging from the equilibrium equations of the full three-dimensional theory. Discussion of the order of magnitude of the errors involved in the membrane approximation is a feature of the analysis. The corresponding incremental equations are also derived as a prelude to their application in certain bifurcation problems. One such problem is examined in the companion paper (Part II) in which results for thick shells and membranes are compared.
TL;DR: In this paper, the temporal evolution of a two-dimensional electrostatic shear instability is numerically studied with special attention to rotational deformation of auroral arcs and momentum transport across the magnetospheric boundary.
Abstract: Temporal evolution of a two-dimensional electrostatic shear instability is numerically studied with special attention to rotational deformation of auroral arcs and momentum transport across the magnetospheric boundary. It is found that the spatial structure of the growing vortex is in good agreement with the small-scale auroral deformation called ‘curl.’ An anomalous viscosity arising from the shear instability is found to be given approximately by 0.08 aV0, where a is the characteristic distance over which the flow velocity changes by V0. If we assume that a = 200 km and V0 = 250 km/s at the magnetospheric boundary, the anomalous viscosity becomes 4 × 1013 cm² s−1, which is comparable to, or even larger than, the value estimated by Axford (1964) from energy requirements of a typical magnetic storm. Spectral energies of fully developed electrostatic turbulence are also studied. It is found that the observed power spectral energies can well be represented by a power law of the form k−4.